The invention concerns a plug-in connection, in particular for fluid lines, comprising a part of the connection to be inserted and a receiving part of the connection, between which a seal can be clamped and which are able to be releasably connected to one another by flexible snap-in elements in a snap-in position
Plug-in connections of this kind are known from practice in a wide variety of forms. To simplify the joining together of plug-in connections, a snap-in connection with resiliently snap-engaging holding elements, which correspond in pairs on the part of the connection to be inserted (xe2x80x9cmalexe2x80x9d part) and on the receiving part of the connection (xe2x80x9cfemalexe2x80x9d part), is usually provided. Normally, flexible snap-in hooks or the like are provided on the receiving part, while the outer contour of the part to be inserted is provided with a step-shaped collar or annular collar, which serves as an abutment for the radially inwardly directed snap-in hooks. At the same time as the joining together, the necessary sealing of such a plug-in connection is ensured by a seal (sealing ring, flat gasket or the like) coming to bear on both sides, even before snap-in engagement of the holding elements, and possibly being compressed radially, at least slightly, before the snap-in position is reached. This achieves radial prestressing of the seal, which prevents any escape of a fluid flowing via the plug-in connection and/or the entry of foreign substances (air, contaminants) into the connected line. Depending on the mechanical loading of the plug-in connection by external forces such as tension/bending or by internal compressive forces in the case of fluidic plug-in connections, the snap-in connection must be very secure. This sometimes gives rise to problems when separating the connection, manual disassembly without tools always been preferable. The part of the connection to be inserted is often provided on its front outer circumference with a bevel, which assists its introduction into the receiving part.
The invention is based on the object of specifying a simple plug-in connection with an improved sealing effect.
accordingly to the invention, the seal can be clamped between a front region of the part of the connection to be inserted and an abutment in the receiving part of the connection. At the same time, the distance of the snap-in elements of the part of the connection to be inserted from the front region of the latter is dimensioned such that the snap-in position can be reached just by slight compression of the seal in the axial direction. This has the advantage that the effective inside diameter of the seal, and consequently also the surface area subjected to internal pressure, is smaller than in the case of a seal which bears only radially on the outside against the part to be inserted, while its end face is completely free. If at least one portion of the seal is in bearing contact between the outer circumferential surface of the front region of the part of the connection to be inserted and the inner circumference of the receiving part of the connection, the connection is less sensitive to slight deviations from the alignment of the two parts of the connection, which may arise for example due to external force effects. The above advantageous effect is achieved in a particularly expedient way if the seal is of an annular design with an unround cross section and with an inside diameter that changes over its axial extent, a portion with a greater inside diameter bearing against the outer circumferential surface of the part of the connection to be inserted. This form has the effect that, toward the part to be inserted, the mouth of the seal forms a funnel contour, which makes it easier for said part to be introduced. The radially drawn-in portion then lies in front of the front end of the part of the connection and forms the axial seal. The seal could be arranged and fastened on the front region of the part to be inserted. It is more expedient, however, because it is better protected against damage before and during the joining together of the plug-in connection, if the seal is fastened in the interior space of the receiving part. The introduction and bringing into contact of the part of the connection to be introduced is made very much easier and the seal remains largely protected from damage if the front outer region, or the front circumferential surface, of the part of the connection to be inserted is provided in a way known per se with a bevel or chamfer. When the chamfered circumferential surface is in contact with the seal and is compressing the latter both in the axial direction and in the radial direction, on the one hand particularly good sealing quality is achieved, on the other hand the necessary joining force is reduced by the wedging effect. A major advantage with regard to quality assurance is achieved if a stop that limits the insertion depth of the part of the connection to be inserted and acts independently of the snap-in means and the seal is provided. Then the part of the connection can be pushed in at most to a fixed depth, the snap-in position already having been reached before this. Inadvertent pinching of the flexible seal is reliably prevented in this way. Of course, such a stop could be provided on the receiving side, in the interior space, or be realized by an additional component. In a particularly simple way, however, this stop is formed by at least one radial projection formed onto the part of the connection to be inserted, for example an annular collar, the outer size of which is greater than the circular opening of the receiving part of the connection.
With regard to the internal bracing of the plug-in connection between the seal and the snap-in elements, it is also of advantage if the snap-in elements can be released from the snap-in engagement by means of releasing aids or lifting-out means that are separate or formed directly on them. This makes the intentional separation of the plug-in connection very much easier. It also avoids damage being caused by improper use of tools and ensures that the parts of the connection can continue to be used after separation.
Production engineering advantages arise if the snap-in hooks and the lifting-out means are integrally formed onto the receiving part of the connection; since all the parts of the plug-in connection are preferably produced from injection-moldable plastic, it is relatively easily possible for such integral snap-in elements with releasing aids to be formed in an injection mold.
In a particularly expedient embodiment, the snap-in hooks and the lifting-out means are connected to the part of the connection via thin webs and are designed as levers which can be flexibly pivoted by pressing in the lifting-out means and twisting the webs. With this configuration, extremely economical use of material is possible, because the snap-in hooks and lifting-out means can be produced as component parts of the outer wall of the receiving part of the connection and can be easily punched free from said outer wall by slits.
A preferred use of these plug-in connections is for establishing low-pressure hose connections in motor vehicles, for example for windshield washing and/or windshield cleaning systems. They may also be used in systems of lines for pneumatic central locking systems or other loads controlled by pressure or negative pressure.
The plug-in connection discussed here would also be suitable, however, for waterproof and pressuretight contacting of electrical conductors, which could be introduced for example along with the required end plug-in contacts into the interior hollow spaces of the parts of the connection.